As magnetic recording storage densities continue to progress in an effort to increase the storage capacity of magnetic storage devices, magnetic transition (i.e., bit) dimensions and critical features of the recording device are being pushed below 100 nm. In some cases, the critical dimensions of the write element are decreasing faster than the spacing between the write element and the magnetic medium. This presents a significant challenge in that not only is the magnetic field strength effectively reduced, but the magnetic field profile at the medium is more poorly confined. The result is that off-track fields can cause undesirable effects such as adjacent track or side track erasure. Thus, an important design consideration is to confine the magnetic fields more effectively without significantly degrading the field strength at the medium.
In addition, making the recording medium stable at higher areal densities requires magnetically harder (i.e., high coercivity) storage medium materials. A magnetically harder medium may be written to by increasing the saturation magnetization value of the magnetic material of the recording device to increase the magnetic field applied to the magnetic medium. However, the rate of increase of the saturation magnetization value is not sufficient to sustain the annual growth rate of bit areal densities. Another approach is to provide a stronger write field by incorporating a conductor adjacent to the tip of the write pole that produces a magnetic field to reduce the coercivity of the magnetic medium near the write pole. This allows data to be written to the high coercivity medium with a lower magnetic field from the write pole. However, due to the finite thickness of the conductor in the down track direction and its location, the magnetic field generated by the conductor can have an adverse effect on the down-track field gradient. In addition, leads that deliver current to the conductor may present potential processing and reliability problems due to exposure of the lead material to corrosion inducing agents. Furthermore, when side shields are incorporated in the writer, a portion of the leads near the medium confronting surface, write pole, and assist device are often replaced with magnetic materials, which generally do not have ideal electrical and thermal properties.